Stockholders' Equity (Stock Options Vested, Or Expected to Vest and Are Exercisable) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2016	Sep. 30, 2016
Stock-Based Compensation
Options outstanding, Number of options	4,792	4,944
Options outstanding, Weighted-Average Exercise Price	$ 35.35	$ 35.35
Options outstanding, Weighted-Average Remaining Life in Years	5 years 10 months 24 days
Options outstanding, Aggregate Intrinsic Value	$ 161,511
Options vested and exercisable, Number of options	3,488
Options vested and exercisable, Weighted-Average Exercise Price Per Share	$ 32.83
Options vested and exercisable, Weighted-Average Remaining Life in Years	5 years
Options vested and exercisable, Aggregate Intrinsic Value	$ 126,348
Options vested and expected to vest, Number of options	4,719
Options vested and expected to vest, Weighted-Average Exercise Price Per Share	$ 35.25
Options vested and to expected vest, Weighted-Average Remaining Life in Years	5 years 9 months 18 days
Options vested and expected to vest, Aggregate Intrinsic Value	$ 159,525